Study on the remediation effect and influencing factors of stabilized biochar supported with nano zero-valent iron on Cr(VI) in groundwater

Nano zero-valent iron (nZVI) has problems such as agglomeration, passivation and poor transportability, which affect the in situ remediation effect of Cr(VI) contaminated groundwater. To develop a low-cost, green nZVI modified material, a low-cost, green modification for nZVI was developed. The nZVI@BC reaction system was constructed by supporting nZVI with ball-milled biochar (BC) as carrier and then stabilized with carboxymethyl cellulose (CMC). CMC-nZVI@BC was synthesized as a novel high-efficiency, anti-passivation nano-scale remediation material. The nZVI before and after modification was characterized and analyzed, and the effects of CMC-nZVI@BC addition, initial concentration of Cr(VI), pH and temperature and chemical fraction of groundwater on the removal of Cr(VI) by CMC-nZVI@BC were investigated, and the mechanism of Cr(VI) removal by CMC-nZVI@BC was elucidated, and the following conclusions were obtained: (1) The best removal of Cr(VI) by nZVI@BC at the Fe and C mass ratio of 2∶1； the removal rate